Sperchopsis tessellata, (ZIEGLER, 1844)

Archangelsky, Miguel, Martínez Román, Nicolás Rafael & Fikáček, Martin, 2021, Larval chaetotaxy and morphology are highly homoplastic yet phylogenetically informative in Hydrobiusini water scavenger beetles (Coleoptera: Hydrophilidae), Zoological Journal of the Linnean Society 192 (2), pp. 416-416 : 416-

SPERCHOPSIS TESSELLATA (ZIEGLER, 1844)

( FIGS 90–98 )

Diagnosis

Larval morphology: Head capsule subquadrate, slightly wider anteriorly; basal surface on dorsal and lateral sides bearing strong cuticular projections; frontal lines Y-shaped, incomplete; coronal line short; nasale slightly asymmetrical, with five short teeth, median teeth smaller, second and fourth teeth projecting farther than remaining ones; lateral lobes of epistome symmetrical, bearing seven stout setae and an inner area of strong and sharp cuticular projections; posterior tentorial grooves close to midline, anterior, close to submentum. Cervical sclerites present. Antenna short, basal antennomere the widest, as long as second and third antennomeres combined, second antennomere bearing a row of sharp inner cuticular projections; sensory appendage short 0.33 × as long as third antennomere. Mandibles symmetrical, with three inner teeth at midlength, basal tooth the smallest. Maxilla with large stipes, slightly longer than palpus, inner margin with an area of short and sharp cuticular projections basally, distally bearing a strong and sharp spine; first palpomere incompletely sclerotized dorsally, bearing an inner appendage twice as long as second palpomere, third palpomere the longest; membrane between second and third palpomeres with a few short and sharp cuticular projections. Labium with submentum fused to head capsule, dorsally with sharp cuticular projections on mentum; basal palpomeres, and membranes between prementum and first palpomere and between first and second palpomeres with short cuticular projections; mentum subtrapezoidal, wider basally; prementum subquadrate, slightly wider apically; ligula well developed, twice as long as first palpomere; second palpomere the longest, 3.0–4.3 × as long as first palpomere. Pronotal plate large, covering most of pronotum, subtrapezoidal, posterior margin wider, with rounded corners and with sagittal line; those of meso- and metathorax smaller, irregularly shaped, both with sagittal line; metathorax with two pairs of posterior lobes, innermost sclerotized; both meso- and metathorax with a pair of lateral lobes on pleural areas. Abdomen mostly membranous ( Figs 7–9 ), segments one to seven with one anterior pair of small dorsal plates and two pairs of small plates bearing short projections each carrying a long distal seta, innermost pair sclerotized; two additional pairs of projections on each lateral and lateroventral margin; dorsal plate of segment eight large, sub-oval; segment nine trilobed, sclerotized dorsally. Legs well developed, fivesegmented. Morphometrics. See Table 3. Chaetotaxy. gFR2 with seven stout setae projecting mediad; pore PA30 behind pore PA29; A2 with three setae near SE1; pore MN4 equidistant to setae MN1 and MN5; gMX2 with six setae; submentum with two or three secondary setae on each side; pore LA11 basal.

Figures

Figures 90–98. Third instar larva of Sperchopsis tessellata. 90–92, head capsule (90, dorsal view; 91, ventral view; 92, labroclypeus). 93, antenna, dorsal view. 94, right mandible, dorsal view. 95–96, maxilla (95, dorsal view; 96, ventral view). 97–98, mentum and prementum (97, dorsal view; 98, ventral view). Scale bars: Figs 90–91: 0.1 mm, Figs 92–98: 0.05 mm.

Figures 1–12. Hydrobiusini larvae, third instar larval habitus in dorsal, lateral and ventral view: 1–3, Hydramara argentina. 4–6, Limnohydrobius melaenus. 7–9, Sperchopsis tessellata. 10–12, Limnoxenus niger. Scale bars: 2 mm.